Adsorption isotherms of benzoic acid onto activated carbon and breakthrough curves in fixed-bed columns

The adsorption isotherms of benzoic acid onto granular activated carbon at varying solution temperatures (25-55 degreesC) and pHs (2-8) from aqueous s olution were experimentally determined by batch tests. The Toth model was f ound to fit all of the experimental data well. A series of column tests wer e performed to determine the breakthrough curves with varying bed depths (3 -6 cm) and water flow rates (21.6-86.4 cm(3)/h). The results show that the half breakthrough time increases proportionally with increasing bed depth b ut decreases inverse proportionally with increasing velocity. The constant- pattern wave approach using the Freundlich isotherm model fits the experime ntal breakthrough curves quite successfully. A correlation was proposed to predict the volumetric mass-transfer coefficient in the liquid phase.